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Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)最新文献

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An effective memetic algorithm for the optimum multiuser detection problem 最优多用户检测问题的一种有效模因算法
Heng-Siong Lim, B. Venkatesh
This work presents a new two-phase, memetic algorithm to solve the maximum-likelihood multiuser detection problem. The algorithm uses a standard evolutionary programming (EP) for the base level search, which makes a quick decision to direct the search towards the optimal region (phase-1). The local optimization by k-opt heuristic local search is then employed to do fine tuning (phase-2). In order to validate the effectiveness of the proposed method, the algorithm is applied to 10- and 20-user synchronous direct-sequence code-division multiple-access (DS-CDMA) systems. The results clearly show that the algorithm not only improves the solution quality but also makes the EP more efficient in terms of number of iterations to reach the global optimum.
本文提出了一种新的两阶段模因算法来解决最大似然多用户检测问题。该算法采用标准进化规划(EP)进行基础级搜索,快速决策,将搜索导向最优区域(阶段1)。然后使用k-opt启发式局部搜索的局部优化进行微调(阶段2)。为了验证该方法的有效性,将该算法应用于10用户和20用户同步直接序列码分多址(DS-CDMA)系统。结果清楚地表明,该算法不仅提高了解的质量,而且在迭代次数方面提高了EP达到全局最优的效率。
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引用次数: 7
Complete complementary code for spread time CDMA system 完整的补充代码扩展时间CDMA系统
Liru Lu, V. Dubey
Spread-time code division multiple access (ST-CDMA) is an alternative CDMA scheme to spread spectrum (SS). The ST-CDMA is proposed for bandlimited multiple access channels, which can be considered the time-frequency dual of SS-CDMA. We propose a new ST-CDMA system based on the orthogonal complete complementary (CC) code. The performance of the proposed system is investigated and the simulation is done to compare with the conventional ST-CDMA system using PN codes. The results show the CC code-based ST-CDMA performs better than the existing system, which can be an additional choice for future multiple access communications systems.
扩频码分多址(ST-CDMA)是扩频码分多址的一种替代方案。ST-CDMA是一种带宽有限的多址信道,可以看作是SS-CDMA的时频对偶。提出了一种基于正交完全互补码的ST-CDMA系统。研究了该系统的性能,并与传统的ST-CDMA系统进行了仿真比较。结果表明,基于CC码的ST-CDMA系统性能优于现有系统,可作为未来多址通信系统的附加选择。
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引用次数: 4
Throughput of the 1x EV-DO system with various scheduling algorithms 不同调度算法下1x EV-DO系统的吞吐量
E. Choi, Wan Choi, J. Andrews
The average sector throughput of the popular 1x EV-DO system with three different scheduling algorithms is mathematically analyzed for a multicell system with lognormal shadowing. The scheduling algorithms considered are round robin, equal latency, and relative fairness. The trade off between throughput and latency among the three scheduling algorithms is illuminated by the analysis, since the key design parameters are identified. From numerical examples, it is shown that the average throughput in a typical urban area is around 600-800 kbit/s. The results of this paper will help engineers do cellular planning and reliably predict throughput for 1x EV-DO and other data-based cellular systems.
对具有对数正态阴影的多cell系统,用三种不同调度算法对流行的1x EV-DO系统的平均扇区吞吐量进行了数学分析。所考虑的调度算法有轮循、等延迟和相对公平性。由于确定了关键的设计参数,因此分析说明了三种调度算法之间的吞吐量和延迟之间的权衡。数值算例表明,典型城市地区的平均吞吐量约为600 ~ 800kbit /s。本文的结果将帮助工程师进行蜂窝规划,并可靠地预测1x EV-DO和其他基于数据的蜂窝系统的吞吐量。
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引用次数: 22
Application of density evolution in turbo-MUD design for overloaded coded CDMA systems 密度演化在超载编码CDMA系统turbo-MUD设计中的应用
S. Morosi, E. Del Re, R. Fantacci, A. Chiassai
An original turbo multiuser detector for overloaded coded DS-CDMA systems is presented and studied: the performance of the proposed system is tested by Monte Carlo simulations and by means of the density evolution theory. The proposed turbo-MUD receiver is based on the use a combination of a linear MMSE detector in the first stages and an interference cancellation scheme in the successive ones. The inputs of both receivers are the soft information from a bank of turbo decoders. The performance of the proposed receiver can be effectively predicted in overloaded communication systems by means of density evolution technique: the use of this technique also permits us to evaluate the proper number of MMSE iterations, making easier the design of the receiver.
提出并研究了一种用于超载编码的DS-CDMA系统的turbo多用户检测器,并通过蒙特卡罗仿真和密度演化理论对该系统的性能进行了测试。所提出的涡轮- mud接收机是基于在第一阶段使用线性MMSE检测器和在后续阶段使用干扰消除方案的组合。两个接收机的输入都是来自一组涡轮解码器的软信息。通过密度演化技术,可以在过载通信系统中有效地预测所提出的接收机的性能:该技术的使用还允许我们评估MMSE迭代的适当次数,使接收机的设计更容易。
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引用次数: 0
Accurate FFT processing window timing detection based on maximum SIR criterion in OFCDM wireless access OFCDM无线接入中基于最大SIR准则的精确FFT处理窗时检测
Satoshi Nagata, N. Maeda, H. Atarashi, M. Sawahashi
The paper proposes an accurate fast Fourier transform (FFT) window timing detection method based on the maximum signal-to-interference power ratio (SIR) criterion, taking into account the received signal power and intersymbol interference, according to different detected FFT window timings in orthogonal frequency and code division multiplexing (OFCDM) wireless access. The SIR of the received signal after FFT processing is estimated using the desired signal power and the intersymbol interference power calculated using the power delay profile, which is measured by the cross-correlation between the pilot symbol replica and the received signal. Furthermore, since the SIR is calculated only for the received path timing of the first path and those paths exceeding the guard interval duration, which are greater than the noise-threshold value, the computational complexity of the proposed method is low. Computer simulation results show that the proposed scheme reduces the required average received signal energy per symbol-to-background noise power spectrum density ratio (E/sub s//N/sub 0/) for achieving the average packet error rate (PER) of 10/sup -2/ by approximately 1.0 dB compared to the conventional method which detects the forward path timing of the power delay profile (16QAM data modulation, six-path Rayleigh fading channel, maximum delay time of 3 microsec, RMS delay spread of 0.86 microsec).
针对正交频码分复用(OFCDM)无线接入中不同检测到的FFT窗时,提出了一种基于最大信干扰功率比(SIR)准则,同时考虑接收信号功率和码间干扰的精确快速傅立叶变换(FFT)窗时检测方法。接收信号经过FFT处理后的SIR使用期望的信号功率估计,并使用功率延迟曲线计算码间干扰功率,该功率延迟曲线由导频符号副本与接收信号之间的相互关系测量。此外,由于SIR仅计算第一条路径的接收路径时间和超过保护间隔持续时间的路径,这些路径大于噪声阈值,因此该方法的计算复杂度较低。计算机仿真结果表明,为了实现10/sup -2/的平均包错误率(per),与传统的功率延迟曲线(16QAM数据调制,六径瑞利衰落信道,最大延迟时间为3微秒)的前向路径定时检测方法相比,该方案将每个符号与背景噪声功率谱密度比(E/sub s//N/sub 0/)所需的平均接收信号能量降低了约1.0 dB。RMS延迟扩展为0.86微秒)。
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引用次数: 2
Evolutionary programming with cloning and adaptive cost function applied to multi-user DS-CDMA systems 基于克隆和自适应代价函数的进化规划在多用户DS-CDMA系统中的应用
Taufik Abrão, Fernando Ciriaco Dias Neto, P. Jeszensky
A new utilization form for the evolutionary programming (EP) algorithm applied to multi-user DS-CDMA (direct sequence code division multiple access) systems in a synchronous AWGN (additive white Gaussian noise) channel is proposed. In order to find the maximum likelihood (ML) solution, the variance matrix for the generation of new candidates was expressed as a function of the following parameters: E/sub b//N/sub 0/; near-far ratio (NFR); cost function (fitness value). A cloning strategy procedure was introduced where the best vectors with the bit-candidates were cloned, reducing drastically the required time for the algorithm convergence to the single user bound (SuB) performance. An improvement in the convergence process was obtained using a parallel interference canceller with soft decision (SD-PIC) for initial vector generation.
提出了一种新的进化规划(EP)算法应用于同步加性高斯白噪声信道下多用户直接顺序码分多址(DS-CDMA)系统的应用形式。为了找到最大似然(ML)解,将新候选生成的方差矩阵表示为以下参数的函数:E/sub b//N/sub 0/;近远比;成本函数(适应度值)。引入克隆策略过程,克隆具有候选位的最佳向量,大大减少了算法收敛到单用户绑定(SuB)性能所需的时间。采用带有软判决的并行干涉消去器(SD-PIC)进行初始矢量生成,提高了收敛速度。
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引用次数: 17
The optimum received signal-power distribution for CDMA packet communication systems employing successive interference cancellation 采用连续干扰消除的CDMA分组通信系统的最佳接收信号功率分配
Y. Tadokoro, H. Okada, T. Yamazato, M. Katayama
In CDMA packet communication systems employing the successive interference cancellation (SIC) scheme, the suppression of MAI depends on the received signal-power distribution, in addition to the cross-correlation characteristics of the spreading sequences and the number of transmitted packets. Some work has been done about discovering the received signal-power distribution which makes MAI be suppressed effectively. This distribution minimizes the averaged bit error rate (BER). However, in packet communication systems, it is important to the performance whether packets can be transmitted successfully or not. Even if the averaged BER is high, many packets can be correctly transmitted. It implies that the optimum distribution on averaged BER does not give the best performance of packet transmission. The received signal-power distribution which gives the best performance of packet transmission is derived. Such a distribution makes clear the limit of performance improvement using SIC.
在采用连续干扰消除(SIC)方案的CDMA分组通信系统中,除传播序列的相互关联特性和传输的分组数外,干扰抑制还取决于接收信号的功率分布。为了有效地抑制微波干扰,在发现接收信号的功率分布方面做了一些工作。这种分布使平均误码率(BER)最小化。然而,在分组通信系统中,数据包能否成功传输对系统的性能有着重要的影响。即使平均误码率很高,也可以正确传输许多数据包。这说明平均误码率上的最优分配并不能提供最佳的分组传输性能。导出了能使分组传输达到最佳性能的接收信号功率分布。这样的分布明确了使用SIC进行性能改进的限制。
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引用次数: 1
An adaptive transmit diversity scheme based on spatial signal combining for TH-PPM UWB 基于空间信号合并的TH-PPM超宽带自适应发射分集方案
S. Niranjayan, A. Nallanathan, B. Kannan
We propose an adaptive transmit diversity scheme for UWB impulse radio (IR), based on free space signal combining, which provides a significant increase in performance compared to the conventional single antenna MRRC receiver. The proposed scheme employs multiple transmitters, which adjust their transmit delays adaptively, in order to achieve perfect overlapping of pulses in space. This scheme uses a single correlator module at the receiver, and hence reduces the hardware complexity significantly, compared to S-RAKE receivers. The purpose behind free space signal combining is to improve the signal strength without multiplying the noise energy at the output of the correlator detector. Therefore, the proposed scheme can provide higher throughput with less complexity.
我们提出了一种基于自由空间信号组合的UWB脉冲无线电(IR)自适应发射分集方案,与传统的单天线MRRC接收机相比,该方案的性能显著提高。该方案采用多发射机自适应调整发射时延,以实现脉冲在空间上的完美重叠。该方案在接收器上使用单个相关器模块,因此与S-RAKE接收器相比,显着降低了硬件复杂性。自由空间信号合并的目的是在不增加相关检测器输出端的噪声能量的情况下提高信号强度。因此,该方案能够以较低的复杂度提供较高的吞吐量。
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引用次数: 3
Intercarrier interference cancellation in OFDM mobile systems OFDM移动系统中的载波间干扰消除
Lan Yang, Ming Chen, Shixin Cheng, Haifeng Wang
Orthogonal frequency division multiplexing (OFDM) is the projected modulation of choice for fourth-generation broadband multimedia wireless systems. However, for mobile applications, channel variations during one OFDM symbol introduce intercarrier interference (ICI), which degrades the performance. This gets more severe as mobile speed, carrier frequency or OFDM symbol duration increases. We analyze ICI for mobile OFDM systems in terms of the complex weighting coefficients, which give the contribution of each transmitter subcarrier to each demodulated subcarrier. Then, we propose a new cancellation method to reduce the effects of Doppler frequency shift. The results show that by using the proposed cancellation scheme, the ICI can be reduced significantly.
正交频分复用(OFDM)是第四代宽带多媒体无线系统的首选投影调制技术。然而,对于移动应用,在一个OFDM符号期间的信道变化会引入载波间干扰(ICI),从而降低性能。随着移动速度、载波频率或OFDM符号持续时间的增加,这种情况变得更加严重。我们用复加权系数来分析移动OFDM系统的ICI,复加权系数给出了每个发射机子载波对每个解调子载波的贡献。然后,我们提出了一种新的对消方法来降低多普勒频移的影响。结果表明,采用所提出的对消方案,可以显著降低干扰系数。
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引用次数: 1
Spreading code detection and blind interference cancellation for DS/CDMA downlink DS/CDMA下行扩频码检测与盲干扰消除
B. Mouhouche, Karim Abed-Meraim, S. Burykh
We propose a new blind interference scheme algorithm suitable for the direct-sequence code-division multiple access (DS/CDMA) downlink. The interferer codes are unknown but the family to which they belong is supposed to be known. The proposed technique is blind in the sense that only the desired user's spreading code is assumed to be known a priori. The remaining parameters required for the interference cancellation such as spreading codes and energies of interfering users are estimated using subspace decomposition and projection on the family of codes. Fast and efficient implementations are discussed. Therefore, unlike standard interference cancellers which can be used only in the uplink, the proposed method can be implemented at the mobile terminal.
提出了一种适用于直接序列码分多址(DS/CDMA)下行链路的盲干扰方案算法。干扰码是未知的,但它们所属的家族应该是已知的。所提出的技术是盲目的,因为只有期望用户的传播代码被假定是先验的。利用子空间分解和码族投影估计干扰消除所需的剩余参数,如扩频码和干扰用户的能量。讨论了快速有效的实现。因此,与只能在上行链路中使用的标准干扰消除器不同,所提出的方法可以在移动终端上实现。
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引用次数: 10
期刊
Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)
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